估计论坛里没几个人知道zigzag指标里这个问题的答案

[zbj]

在zigzag指标代码中，有这样一段代码，请问，为什么要判断二次 counted_bars==0 ？第一次counted_bars==0 && downloadhistory和第二次counted_bars==0的作用是什么？

if (counted_bars==0 && downloadhistory) // history was downloaded
{

ArrayInitialize(ZigzagBuffer,0.0);
ArrayInitialize(HighMapBuffer,0.0);
ArrayInitialize(LowMapBuffer,0.0);
Print(counted_bars);
}
if (counted_bars==0)
{

limit=Bars-ExtDepth;
downloadhistory=true;
Print(counted_bars);
}